Kate was admitted earlier this afternoon to the private KingEdward VII Hospital in Central London with hyperemesis gravidarum — otherwise known as acute morning sickness — which requires supplementary hydration and nutrition.

Clarence House said the pregnancy is in its “very early stages,” and that the duchess is expected to stay in hospital for several days. She will require a period of rest thereafter.

No matter the sex of the child, it will succeed to the throne, as the British parliament has agreed to pass a law for equality.

Commonwealth heads of government agreed to change the rules of succession at a summit in Perth, Australia earlier this year, meaning the royal couple’s first-born child would become monarch regardless of its sex.

Under the old rules — in place for three centuries — a younger son would beat his older sister to the throne.